Pests (invertebrates, insects, arachnids, larvae thereof, etc.) are annoying to humans for a myriad of reasons. They have annually cost humans billions of dollars in crop losses and in the expense of keeping them under control. For example, the losses caused by pests in agricultural environments include decreased crop yield, reduced crop quality, and increased harvesting costs.
Over the years, synthetic chemical pesticides have provided an effective means of pest control. For example, one approach teaches the use of complex, organic insecticides, such as disclosed in U.S. Pat. Nos. 4,376,784 and 4,308,279. Other approaches employ absorbent organic polymers for widespread dehydration of the insects. See, U.S. Pat. Nos. 4,985,251; 4,983,390; 4,818,534; and 4,983,389. Use of inorganic salts as components of pesticides has also been tried, as disclosed in U.S. Pat. Nos. 2,423,284 and 4,948,013, European Patent Application No. 462 347, Chemical Abstracts 119(5):43357q(1993) and Farm Chemicals Handbook, page c102 (1987).
However, it has become increasingly apparent that the widespread use of synthetic chemical pesticides has caused detrimental environmental effects that are harmful to humans and other animals. For instance, the public has become concerned about the amount of residual chemicals that persist in food, ground water and the environment, and that are toxic, carcinogenic or otherwise incompatible to humans, domestic animals and/or fish. Moreover, some target pests have even shown an ability to develop immunity to many commonly used synthetic chemical pesticides. In recent times, regulatory guidelines have encouraged a search for potentially less dangerous pesticidal compositions via stringent restrictions on the use of certain synthetic pesticides. As a result, elimination of effective pesticides from the market has limited economical and effective options for controlling pests. As an alternative, botanical pesticides are of great interest because they are natural pesticides, i.e., toxicants derived from plants that are safe to humans and the environment.
With respect to house dust mites, the safety issue is even more critical. The American house dust mite, Dermatophagoides farinae (Hughes), and European house dust mite, D. pteronyssinus (Trouessart), are the dominant mite species occurring in human dwellings and they are the anthropod group most responsible for producing allergens contained in house dust. The allergens are primarily found in the fecal matter of dust mites and may cause a variety of adverse reactions in humans, including asthma. Moreover, recent medical literature has proven that house dust mites are a natural byproduct of the scalp, including humans, and treatment of the environment alone will not eliminate house dust mites. The conventional pesticides are not a viable alternative for house dust mites for a variety of reasons, including the fact that any treatment will necessarily come in contact with humans and animals, and may cause more severe reactions than the dust mite to be treated.
Accordingly, there is a great need for novel pesticidal compositions, containing no pyrethrum, synthetic pyrethroids, chlorinated hydrocarbons, organo phosphates, carbamates and the like, to be used inside the home and on mammals as a contact pesticide against house dust mites. In addition, there is a need for a method of treating the scalp and skin of mammals to kill and repel mites, as a prophylactic measure.